1. Field of the Invention
The present invention relates to a method of differential unitary space-time modulation by encoding messages to transmit through multiple transmit antenna into multiple trellis code in a communication system wherein the signals are transmitted between multiple transmit antennas and at least one receive antenna.
2. Prior Art
Differential unitary space-time modulation (DUSTM) is a scheme proposed for the transmit antenna diversity to combat detrimental effects in wireless fading channels at a receiver without channel state information. In the DUSTM, the transmitted signal matrix at each time block is the product of the previously transmitted signal matrix and the current unitary data matrix. The constellations for unitary space-time modulated signals form groups under matrix multiplication.
Since the proposal of the DUSTM, several works to improve performance of the DUSTM have been introduced.
However, the performance of DUSTM in a communication system wherein the signals are transmitted and received between multiple transmit antennas and at least one receive antenna is not satisfactory.